I'm mixed on this :), but here are some thoughts:

1) I do like working examples very much - @WouterJ - you know me now ;)
2) If the XML examples get VERY long, it's ok - the code blocks default to the height of the default one shown. So the page will only get pushed down if you change over to XML. So, there's no immediate disadvantage
3) The XML examples would be a bit harder to read, but since they would also be functional, I think it's a net gain. Also, if you're used to XML, it may be more clear in some ways since you will see all the elements you expect.

For me, it makes sense to add these, but only if someone wants to take the effort to do it. There are bigger things to work on, but I do think that it would be an improvement. It could also be something that was done over time if the precedent were set.

Thanks guys!